Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenue from External Customer [Line Items]
Typical contract length	30 days
Allowance for contractual discounts against outstanding accounts receivable	$ 116.5		$ 123.8
Allowance for uncompensated care against outstanding accounts receivable	51.6		51.9
Value of uncompensated care services qualified as charity care	1.9		1.5
Estimated cost of providing charity services	$ 0.5	$ 0.4
Percentage of reserve for receivables outstanding more than nine months (percent)	100.00%
Oil and Gas [Member]
Revenue from External Customer [Line Items]
Accounts receivable, net	$ 75.8		74.1
Air Medical [Member]
Revenue from External Customer [Line Items]
Allowance for contractual discounts against outstanding accounts receivable	116.5		123.8
Allowance for uncompensated care against outstanding accounts receivable	51.6		51.9
Accounts receivable, net	90.4		90.2
Technical Services [Member]
Revenue from External Customer [Line Items]
Accounts receivable, net	$ 3.1		$ 4.1
Minimum [Member]
Revenue from External Customer [Line Items]
Accounts receivable invoice term	30 days
Minimum [Member] | Oil and Gas [Member]
Revenue from External Customer [Line Items]
Typical contract length	1 year
Maximum [Member]
Revenue from External Customer [Line Items]
Accounts receivable invoice term	60 days
Maximum [Member] | Oil and Gas [Member]
Revenue from External Customer [Line Items]
Typical contract length	7 years